Background: This article describes the barriers and facilitating factors to the adoption, implementation and continuation of the Dutch Obesity Intervention in Teenagers (DOiT) programme in the Netherlands. Methods: We evaluated the adoption, implementation and continuation of the programme at 20 voluntary prevocational schools, which adopted the programme. Interviews were conducted with DOiT coordinators and/or teachers (n = 44) at the end of the first and second school year of the 2-year implementation period. Interviews were recorded and transcribed verbatim. Data were coded by two researchers independently. Identified barriers and facilitating factors were categorized into four groups: (i) organizational factors, (ii) individual factors, (iii) characteristics of the programme and (iv) characteristics of the implementation strategy. Results: Teachers and DOiT coordinators identified various implementation barriers (e.g. lack of planning, other urgent unforeseen priorities, no plan to cope with teacher turnover and high teacher workload) as well as facilitating factors (e.g. involvement of DOiT coordinator and support from the DOiT office, sufficient communication and collaboration between teachers, strong teacher motivation and flexibility of the programme). Conclusion: Overall, DOiT implementers were satisfied with the compatibility, layout, content and potential for tailoring the programme. Barriers for successful implementation were mainly at the school and teacher level. Findings of this study can be used for further improvement of the DOiT programme and for the development and improvement of other health promotion programmes in the school setting.